SysLock Virus

 Virus Name:  SysLock 
 Aliases:     3551, 3555 
 V Status:    Endangered 
 Discovered:  November, 1988 
 Symptoms:    .COM & .EXE growth; data file corruption 
 Eff Length:  3,551 Bytes 
 Type Code:   PNA - Encrypting Non-Resident .COM & .EXE Infector 
 Detection Method:  ViruScan, F-Prot, AVTK, NAV, Sweep, IBMAV, 
                    NAVDX, VAlert, PCScan, ChAV, 
                    NShld, LProt, Sweep/N, Innoc, NProt, AVTK/N, 
                    NAV/N, IBMAV/N 
 Removal Instructions:  F-Prot, or delete infected files 
 General Comments: 
       The SysLock virus is a parasitic encrypting virus which infects 
       both .COM and .EXE files, as well as damaging some data files on 
       infected systems.  This virus does not install itself memory 
       resident, but instead searches through the .COM and .EXE files and 
       subdirectories on the current disk, picking one executable file at 
       random to infect.  The infected file will have its length increased 
       by approximately 3,551 bytes, though it may vary slightly 
       depending on file infected. 
       The SysLock virus will damage files by searching for the word 
       "Microsoft" in any combination of upper and lower case characters, 
       and when found replace the word with "MACROSOFT". 
       If the SysLock virus finds that an environment variable "SYSLOCK" 
       exists in the system and has been set to "@" (hex 40), the virus 
       will not infect any programs or perform string replacements, but 
       will instead pass control to its host immediately. 
       Known variant(s) of SysLock are: 
       Advent: Reported to be a SysLock variant, the sample of this virus 
               received by the author does not replicate.  All known 
               samples of this virus available from anti-viral researchers 
               also do not replicate.  Fridrik Skulason of Iceland has 
               indicated that this virus will only replicate it is on an 
               infected .EXE file, and then it will only infect .COM 
               files.  This variant is thought to be extinct. 
       Advent-B: Received from the NCSA is September, 1991, Advent-B 
               is a bug fixed version of the Advent variant.  Advent-B 
               may infect one .COM or .EXE program in the current 
               directory each time an infected program is executed. 
               It will, however, only infect the first few files in the 
               current directory.  Infected files will increase in size by 
               2,768 to 2,783 bytes with the virus being located at the 
               end of the infected program.  The program's date and time 
               in the disk directory will not be altered.  Like Advent, 
               Advent-B will activate in December, at which time it will 
               randomly activate, displaying four candles and playing 
               "On Tannenbaum" on the system speaker. 
       Cookie: Based on the SysLock virus, Cookie is a variant which is 
               considerably shorter in length.  It is a non-resident, 
               direct action infector of .COM and .EXE programs, including 
               COMMAND.COM.  It infects one .COM or .EXE program located in 
               the current directory each time an infected program is 
               executed.  Infected programs will have a file length increase 
               of 2,232 to 2,251 bytes with the virus being located at the 
               end of the file.  The file's date and time in the DOS disk 
               directory listing.  Systems infected with Cookie may 
               experience system hangs when some infected programs are 
               executed.  In some cases, the infected program will stop 
               functioning properly after a number of executions.  This 
               virus has been reported to display the message "I want a 
               COOKIE!", though the sample received doesn't exhibit this 
               Origin:  Europe  January, 1991. 
       Macho-A: same as the SysLock virus, except that "Microsoft" is 
               replaced with "MACHOSOFT". 

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